Breath actuated nebulizer for ventilator circuit

ABSTRACT

A ventilator circuit apparatus is provided for the administration of an aerosolized drug from a nebulizer through an endotracheal tube to a patient on a mechanical ventilator with humidification of the breathing gases. Means to disconnect the nebulizer without interrupting the airflow to the patient is provided, with a T-fitting and three-way valve in the ventilator circuit that permits the nebulizer to be bypassed by the airflow, allowing the nebulizer to be removed from the apparatus without interrupting the flow of breathing gases to the patient. In embodiment, the nebulizer is breath-enhanced jet nebulizer. In an embodiment, the jet nebulizer is breath-actuated, by the use of an air pressure sensor that toggles the flow of pressurized air to the nebulizer that drives the jet required for nebulization.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority to U.S. Patent Application62/681,654, filed Jun. 6, 2018.

FIELD OF THE INVENTION

This invention pertains to the administration of nebulized drugs topatients connected to a mechanical ventilator breathing circuit.

BACKGROUND

The administration of nebulized drugs to patients on a mechanicalventilator is an important medical need. Challenges in theadministration of nebulized drugs to patients on a mechanical ventilatorinclude maximizing efficient delivery of the drug to the lungs of thepatient and provision of properly humidified breathing gases.Inefficient drug delivery wastes drug product, which may be expensive,may cause unpredictable dosing to patients (too much or too littledrug), and may cause undesirable exposure of drug to surroundingpersons. As used herein, the term “nebulized” is also referred to as“atomized” or “aerosolized,” and all three terms are interchangeable.The term “drug” as used herein is interchangeable with “pharmaceuticalcomposition.”

Prior art approaches to administering nebulized drugs to patients on aventilator typically involve nebulizers incorporated into a breathingcircuit. Among the challenges of the administration of nebulized drugsin a breathing circuit are maintaining appropriate humidification andminimizing the variability in drug delivery to the patient.

Normally, patients on a mechanical ventilator require humidification ofthe inspired air or other gases. However, the nebulization of many drugswith humidification may be a problem. The humidification can interferewith the formation and transfer of appropriately sized droplets of anatomized drug composition. Thus, in many cases, it is desirable tonebulize a drug composition without humidification.

Another issue is managing the ventilator circuit to minimizeinterruption to the breathing of the patient. It is typically desirableto remove a nebulizer to refill it or clean it. At the same time,turning off the entire circuit, even momentarily, can be a problem forpatients on a mechanical ventilator.

Nebulized aerosol delivery during mechanical ventilation results inprofound unregulated aerosol losses, which are a strong function of dutycycle or the inhalation-exhalation (I/E) ratio, bias flow, andhumidification. Previous studies have suggested that humidificationduring nebulization may reduce drug output (T. G. O'Riordan, G. C.Smaldone, et al., “Nebulizer Function during Mechanical Ventilation,” AmRev Respir Dis. 1992 May; 145(5):1117-22,https://doi.org/10.1164/ajrccm/145.5.1117, PubMed 1586056; P. Diot andG. C. Smaldone et al., “Albuterol Delivery in a Model of MechanicalVentilation,” Am J Respir Crit Care Med 1995, 152, 1391-1394, doi:10.1164/ajrccm.152.4.7551401; D. D. Miller, G. C. Smaldone et al.,“Aerosol Delivery and Modern Mechanical Ventilation, In Vitro/In VivoEvaluation,” Am J Respir Crit Care Med, 2003, 168, 1205-1209, doi:10.1164/rccm.200210-1167OC (see table 1)).

Ventilation circuits have previously been described in, e.g., US2014/0238397 A1, published Aug. 24, 2014, and US 2015/0108670 A1,published Apr. 23, 2015.

SUMMARY OF THE INVENTION

The present invention describes a novel ventilator circuit thatminimizes the influences of duty cycle or the inhalation-exhalation(I/E) ratio, bias flow, and humidification by utilizing a design thatresults in aerosol generation primarily during inspiration (breathenhancement) and minimizes expiratory losses (breath-actuation). Thecircuit facilitates control of supplemental humidification and functionsindependently of the brand of the ventilator.

Also, in view of the references cited above (O'Riordan, Diot, andMiller), suggesting that humidification during nebulization on breathingcircuits with mechanical ventilation may reduce drug output, the instantinvention is designed to provide the benefits of dry nebulization,humidification as required, and isolation of the nebulizer for efficientremoval without interrupting the breathing.

In a first aspect, a ventilator circuit apparatus is provided for theadministration of nebulized drugs through an endotracheal tube to apatient on a mechanical ventilator that controls breathing gases to thepatient. The apparatus has a breathing circuit with an inspiratory limband exhalation limb connected to the ventilator; a nebulizer on theinspiratory limb interposed between a T-fitting and a three-way valvesuch that the nebulizer can be removed from the inspiratory limb withoutinterrupting the flow of breathing gases to the patient; and ahumidifier or heat and moisture exchanger (HME) on the inspiratory limbinterposed between the nebulizer and the endotracheal tube. In anembodiment, all breathing gases to the patient flow through theventilator circuit. In an embodiment, the nebulizer is a jet-nebulizer.In an embodiment, the nebulizer is breath-actuated, further comprising apressure sensor interposed between the nebulizer and the ventilator,wherein the pressure sensor controls a pressurized air supply to thenebulizer required for nebulization to occur, such that nebulizationonly occurs during a pressure increase on the inspiratory limb caused byan increase in air pressure from the ventilator to force an inhalationby the patient. In an embodiment, the nebulizer is breath-enhanced.

In another aspect, a ventilator circuit apparatus is provided for theadministration of nebulized drugs through an endotracheal tube to apatient on a mechanical ventilator that provides breathing gases forinhalation by the patient. In an embodiment, the apparatus has aninspiratory tube connected to an endotracheal tube intubated into apatient; a ventilator circuit comprising a T-fitting with threeconnections, wherein a first connection to the T-fitting is connected tothe inspiratory tube, wherein a second connection of the T-fitting isconnected to the output port of a humidifier, and wherein a thirdconnection of the T-fitting is connected to the output port of anebulizer; wherein the input port of the nebulizer is connected to athree-way valve, and wherein a second connection of the three-way valveis connected to the input port of the humidifier, and wherein a thirdconnection of the three-way valve is connected to an inspiratory outputof the mechanical ventilator; wherein in a first position of thethree-way valve, the circuit is open that bypasses the nebulizer anddirectly connects the inspiratory output of the mechanical ventilator tothe humidifier, and in a second position of the 3-way valve, theinspiratory output of the mechanical ventilator bypasses the humidifierand is directed to the nebulizer; wherein in the second position of thethree-way valve, a drug solution in the nebulizer is nebulized todeliver nebulized drug to the inspiratory tube wherein the nebulizeddrug is inhaled by the patient; and wherein in the first position of thethree-way valve, humidified breathing gases are delivered to theinspiratory tube. In an embodiment, a temperature sensor is provided onin the inspiratory tube that controls the amount of water vapor producedby the humidifier. In an embodiment, one or two connections to theT-fitting have a spring-loaded self-sealing fitting, permitting a tubeinserted in the connection to be pulled out, whereupon the connection toself-seals.

In another aspect, a ventilator circuit apparatus is provided for theadministration of nebulized drugs through an endotracheal tube to apatient on a mechanical ventilator that provides breathing gases forinhalation by the patient. In this embodiment, the apparatus has aninspiratory tube in fluid communication with an endotracheal tubeintubated into a patient; a ventilator circuit comprising a T-fittingwith three connections, wherein a first connection to the T-fitting isconnected to the inspiratory tube, wherein a second connection of theT-fitting is connected to a three-way valve, and wherein a thirdconnection of the T-fitting is connected to the output port of anebulizer; wherein the input port of the nebulizer is connected to thethree-way valve, and wherein a third connection of the three-way valveis connected to an inspiratory output of the mechanical ventilator;wherein in a first position of the three-way valve, the circuit is openthat bypasses the nebulizer and directly connects the inspiratory outputof the mechanical ventilator to the inspiratory tube, and in a secondposition of the 3-way valve, the inspiratory output of the mechanicalventilator is directed to the nebulizer; and wherein in the secondposition of the three-way valve, a drug solution in the nebulizer isnebulized to deliver nebulized drug to the inspiratory tube wherein thenebulized drug is inhaled by the patient. In an embodiment, a heat andmoisture exchanger (HME) with a bypass mode is on the inspiratory tubesuch that when the three-way valve is in the first position, the HMEdelivers humidified breathing gases to the patient, and when thethree-way valve is in the second position, the HME is switched to bypassmode.

In another aspect, the ventilator circuit apparatus for theadministration of nebulized drugs through an endotracheal tube to apatient on a mechanical ventilator that provides breathing gases forinhalation by the patient. In this embodiment, the apparatus has aninspiratory tube connected to an endotracheal tube intubated into apatient; a ventilator circuit comprising a T-fitting with threeconnections, wherein a first connection to the T-fitting is connected tothe inspiratory tube, wherein a second connection of the T-fitting isconnected by a tube to a first connection on a three-way valve, andwherein a third connection of the T-fitting is connected to the outputport of a nebulizer; wherein the input port of the nebulizer isconnected to a second connection of the three-way valve, and wherein athird connection of the three-way valve is connected to an inspiratoryoutput of the mechanical ventilator; wherein in a first position of thethree-way valve, the circuit is open that bypasses the nebulizer anddirectly connects the inspiratory output of the mechanical ventilator tothe inspiratory tube, and in a second position of the 3-way valve, theinspiratory output of the mechanical ventilator is directed to thenebulizer; and wherein in the second position of the three-way valve, adrug solution in the nebulizer is nebulized to deliver nebulized drug tothe inspiratory tube wherein the nebulized drug is inhaled by thepatient. In an embodiment, a ball-valve is interposed between theT-fitting and the nebulizer. In an embodiment, a ball-valve isinterposed between the T-fitting and the nebulizer, and when thethree-way valve is in position one and the ball valve is closed, thenebulizer can be removed from the ventilator circuit withoutinterrupting the flow of breathing gases to the patient. In anembodiment, a temperature sensor is provided on in the inspiratory tubethat controls the amount of water vapor produced by the humidifier. Inan embodiment, the apparatus has an HME.

In another aspect, a method is provided of administering a nebulizeddrug with any of the apparatus embodiments of this invention.

In embodiments, the present invention uses breath-enhanced nebulizers.In an embodiment, the nebulization may be breath-activated. Prior artbreath-enhanced nebulizers have only been used with spontaneouslybreathing patients. Using a breath-enhanced nebulizer with a mechanicalventilator and a breathing circuit allows further enhances the patient'sberating and facilitates the desired drug intake.

The present inventors have found that breath-enhanced nebulizers, suchas those disclosed in this invention, can significantly increase thefraction of drug that is inhaled by the patient and delivered to thelungs (as measured by an inhaled mass (IM) filter in a test apparatus).Moreover, the BEN can significantly shorten the time required tonebulize a particular dose of medication, which can be a significantadvantage to the care facility.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a ventilator circuit of this inventionwith the inhaled air flow directed to a nebulizer.

FIG. 2 is a schematic view of the embodiment of the ventilator circuitof FIG. 1, but with the inhaled air flow bypassing the nebulizer anddirected through a humidifier.

FIG. 3 is a schematic view of an embodiment of a ventilator circuit withthe inhaled airflow directed to the nebulizer and passing through a heatand moisture exchanger (HME).

FIG. 4 is a schematic view of the embodiment of the ventilator circuitof FIG. 3 with the inhaled air flow bypassing the nebulizer and passingthrough an HME.

FIG. 5 is a schematic view of an embodiment of a ventilator circuit witha T-fitting and a ball valve.

FIG. 6 is a schematic view of a portion of the ventilator circuit ofFIG. 5 showing the air flowing through the nebulizer and the ball valveduring inhalation while the nebulized drug is being provided by thenebulizer.

FIG. 7 is a schematic view of a portion of the ventilator circuit ofFIG. 5 showing the air flow bypassing nebulizer and passing through thehumidifier.

FIG. 8 is a schematic view of a portion of the ventilator circuit ofFIG. 5 showing the three-way valve and ball valve configured so that thenebulizer is isolated from the circuit and can be removed withoutinterrupting the circuit.

FIG. 9 is a schematic view of the ventilator circuit of FIG. 5 without ahumidifier showing the air flow during inhalation. An HME would be usedin this embodiment.

DETAILED DESCRIPTION

Disclosed herein is a breathing circuit for the administration ofnebulized drugs to a patient breathing with the aid of a mechanicalventilator and a breathing circuit. In an embodiment, part of thecircuit is a nebulizer, which nebulizes a drug solution for inhalationof the drug by a patient. In an embodiment, the nebulizer is a jetnebulizer that nebulizes drug solutions by shear forces from acompressed air supply to the nebulizer jet. In an embodiment, thenebulizer is another type of nebulizer, for example, a vibrating meshnebulizer or an ultrasonic nebulizer.

In operation, a three-way valve may be included that has two operatingpositions. A second position directs all ventilator flow to thenebulizer resulting in an aerosol generation, which may be limited tonebulization during the inhalation portion of a breathing cycle only. Ina first operating position of the three-way valve, the breathing gasesfrom the ventilator bypass the ventilator and pass instead eitherdirectly to the inspiratory limb of the breathing circuit, or pass tothe inspiratory limb through a humidifier. In an embodiment, specialconnections in the ventilator circuit bypass the nebulizer and allow fornebulizer removal for servicing without breaking the air flow in thecircuit or interrupting breathing to the patient.

In an embodiment, the nebulizer used in this invention is ajet-nebulizer and generates aerosol by nebulization only when anebulizer air flow is provided. An exemplary nebulizer is that disclosedin co-pending patent application [ ], filed [ ], and based on U.S.Provisional Patent Application No. 62/681,654 filed Jun. 6, 2018. Asdisclosed therein, breath-enhanced and breath-actuated nebulizers areprovided.

Breath-enhanced nebulizers have an internal configuration that enhances,or amplifies, the rate of nebulization compared to prior art jetnebulizers. Embodiments of breath-enhanced nebulizers are disclosed inco-pending patent application [ ], based on U.S. Provisional PatentApplication No. 62/681,654. Other types of nebulizers may also be usefulin this invention, including other jet nebulizer designs, vibratingmesh, and ultrasonic nebulizers that can be used in a breathing circuitcontrolled by a mechanical ventilator.

In an embodiment, the nebulization is breath actuated. With a breathactuated nebulizer, compressed air is only provided to the nebulizerwhile the patient is inhaling. This is controlled with a pressure sensorthat toggles the nebulizer air flow on or off as required. Theinhalation portion of a breathing cycle is also termed the “duty cycle,”the fraction of time of an overall inhalation/exhalation cycle when thepatient is actually inhaling. In an embodiment, breath-actuation relieson a pressure sensor that can detect when a patient is inhaling, asopposed to exhaling or neither inhaling nor exhaling, and the sensor canactivate a solenoid that provides compressed air to the nebulizer. In anembodiment, the pressure sensor is placed on a tube in fluidcommunication with the inspiratory outlet of the mechanical ventilator.When the ventilator causes the patient to inhale by increasing the airpressure at the inspiratory outlet, the pressure sensor detects thisincrease and switches on a nebulizer air flow to the nebulizer, whichdrives the jet nebulizer and causes nebulization to occur. Other meansof toggling nebulization are possible with other types of nebulizers.For example, with an electrically driven vibrating mesh or ultrasonicnebulizer, a pressure sensor can control the power supply that drivesthe nebulization.

In an aspect of this invention, the nebulized drug is provided by theinventive breathing circuits in such a way the humidification is notused during nebulization. This may be a desirable feature based onprevious studies (O'Riordan, Diot, and Miller, cited above) suggestingmuch lower nebulizer efficiency if a humidifier is placed before thenebulizer, so that humidified air or other breathing gases enter thenebulizer. As used herein, the term “breathing gases” means eitherordinary air or another breathing gas mixture indicated for use inmechanical ventilation, such as oxygen enriched air.

In an embodiment of this invention, the entire mass of breathing gasesin the inspiratory tract passes through the nebulizer when the nebulizeris active.

In an embodiment of this invention as shown in FIGS. 1-3, a ventilatorcircuit apparatus 100 is provided for the administration of nebulizeddrugs through an endotracheal tube to a patient on a mechanicalventilator 102 that controls breathing gases to the patient. Theapparatus has a breathing circuit with an inspiratory limb 107 andexhalation limb 119 connected to the ventilator 102; a nebulizer 101 onthe inspiratory limb interposed between a T-fitting and a three-wayvalve such that the nebulizer can be removed from the inspiratory limbwithout interrupting the flow of breathing gases to the patient; and ahumidifier 121 or heat and moisture exchanger (HME) (125, FIGS. 3-5) onthe inspiratory limb interposed between the nebulizer and the breathingtube 108, which in turn is in fluid communication with the endotrachealtube intubated in a patient. In an embodiment, all breathing gases tothe patient flow through the ventilator circuit.

In clinical practice, an endotracheal tube would be used by a patient ona ventilator circuit such as disclosed in FIGS. 1-9. The breathing tube108 would connect to the endotracheal tube. For experimental purposes, asimulated lung 110 may be used, and various measurement devices (111 and112) may be used (discussed below). An expiratory line (limb) 119 isalso attached to the breathing tube 108 through Y-connector 127conducting the exhaled air to the ventilator expiratory input port 104.

In an embodiment, nebulizer 101, as discussed herein, produces anaerosol (when active) that is shunted through a T-fitting 106 to theinspiratory line 107 and the endotracheal tube 108 positioned downstreamof the inspiratory line 107 where it is inhaled by the patient 110.

In an embodiment, the nebulizer 101 is breath-actuated, furthercomprising a pressure sensor 114 interposed between the nebulizer 101and the ventilator 102 wherein the pressure sensor controls apressurized air supply 117 to the nebulizer required for nebulization tooccur, such that nebulization only occurs during a pressure increase onthe inspiratory limb caused by an increase in air pressure from theventilator to force an inhalation by the patient. In an embodiment,pressure sensor 114 is in electronic communication with solenoid valve116 via electrical connection 115 that toggles the supply of compressedair 117 on and off. When the pressure at 114 increases, signaling aninhalation phase of the breathing cycle, pressure sensor 114 activatessolenoid 116 to toggle on, supplying compressed air 117 to nebulizer 101via nebulizer air supply line 118, which causes nebulization to start.When the ventilator reduces the air pressure at port 103, pressuresensor 114 detects that the inhalation phase has stopped, and solenoidvalve 116 toggles off stopping the compressed air to nebulizer 101,which stops nebulization. Nebulization will not take place with jetnebulizer 101 unless air supply line 118 is active.

In an embodiment where a jet nebulizer is used, nebulizer compressed air117 typically at 50 psig is used to drive the jet. Nebulizer flows of 2L/min in the continuous mode and 3.5 L/min during breath actuation(typical rates; other flow rates are possible) are used with jetnebulizers.

In an embodiment, the nebulizer is breath-enhanced, which is discussedabove.

In an embodiment, humidifier 121 supplies properly humidified breathinggases to the patient, ideally at 100% humidity and 37° C. at Y-connector127. Regulation of the amount of humidity in the circuit is important.With too much humidity, water will tend to condense inside the circuitwhich is undesirable. With too little humidity, the patient will beuncomfortable and secretions can increase. The humidity may becontrolled, at least in part, by temperature sensor 128 in Y-connector127, that is linked to the humidifier by wire 129. In addition,inspiratory limb 107 may include internal heating elements to heat thebreathing gases to an appropriate temperature.

In an alternative embodiment, instead of a humidifier, a heat andmoisture exchanger (HME) 125 may be employed. This is illustrated inFIGS. 3 and 4. The HME is a device capable of recycling moisture fromthe expiratory air from a patient. In an embodiment, the HME has abypass mode, in which the humidification feature is turned off and thebreathing gases simply pass through. This is necessary when thenebulization is active. When the nebulizer is active, as shown in FIG.3, the HME would be in bypass mode, since nebulized drug cannot passthrough the internal membranes in an HME. Thus, in clinical use, the HMEwould be active in the gas flow configuration shown in FIG. 4, where thenebulizer is bypassed, to provide humidified breathing gases to thepatient. This may be a default mode of operation since the time when anebulizer is being used (i.e., as shown in FIG. 3) may only be for oneor two hours per day.

In the operation of the three-way valve 105, during the inhalation phaseof a breathing cycle, breathing gases from the mechanical ventilatorinspiratory output port 103 are directed to the three-way valve with astopcock 105. As shown in FIGS. 1-4, the three-way valve 105 has twomodes. In the first mode (termed herein the first position), thethree-way valve 105 is configured so that the breathing gases bypass thenebulizer and are shunted through the humidifier 121 (FIG. 2), ordirectly to an HME 125 in the active mode (FIG. 4). In the other mode ofvalve 105 (termed herein the second position), the breathing gases areshunted to nebulizer 101 as shown in FIGS. 1 and 3. Nebulization mayoccur at this stage either in breath-actuated mode or continuousnebulization mode.

In an embodiment, a closed system suction device 128, may be attached tothe breathing tube 108 to allow the removal of secretions from the upperrespiratory tract without having to open the ventilation circuit.

For studies of the performance of the inventive configuration and/orvarious nebulizers, an inhaled mass filter (IM filter) 111 and a Cascadeimpactor 112 attached to the breathing tube 108 can be used to measurethe dose of drug delivered to the patient (FIG. 1). A vacuum pump 113can be attached to the cascade impactor 112. The inhaled mass filtertraps nebulized particles where they can be measured either by weight orby e.g., scintillation counting for radiolabeled nebulized material. Acascade impactor measures the droplet size of the aerosol just beforereaching the simulated patient. In clinical practice, the IM filter andcascade impactor would not be used.

FIG. 2 shows the same apparatus as provided in FIG. 1, but with thethree-way valve 105 in the first position, bypassing the nebulizer 101.In FIG. 2, the inspiratory air flow passes through humidifier 121 viahumidifier inlet 122 and outlet 123. The airflow path moves through aT-fitting 106 to the inspiratory line 107 and the breathing tube 108where it is inhaled by the patient.

In an embodiment, the T-fitting has one or two spring-loadedself-sealing fittings. Such fittings include an internal mechanismopening the airway when a tube is inserted into the fitting. When thetube is removed, a valve closes from the force of a spring, sealing theopening. In an embodiment, a spring-loaded self-sealing fitting 132 ispositioned at the T-fitting connection attached to the nebulizer. In anembodiment, another spring-loaded self-sealing fitting 124 is used atthe T-fitting connection attached to the humidifier. With theseself-sealing fittings, the attachment to the T-fitting 106 can beremoved by separating the two parts, or pulling the connection off theT-fitting, whereupon the T-fitting branch self-seals. This arrangementallows for the removal of the nebulizer or humidifier for (but not both)without interruption to the breathing of the patient. Removal of thenebulizer is most important and may be necessary on a routine basis toreplenish the drug solution in the nebulizer.

The self-sealing T-fitting can play a critical role in the overalloperation of the ventilator circuit embodiments as described herein. Itis necessary to periodically remove the nebulizer from the ventilatorcircuit, for example, to replace it, to clean it, or to refill it. Atthe same time, a patient on mechanical ventilation is depending on theventilator and the associated apparatus for their air for their lungs,which ideally is not interrupted, even for a few seconds. Accordingly,disassembling a ventilator circuit can be a problem. Removing a fittingto replace a routine must be done as quickly as possible. By the use ofthe spring-loaded T-fitting as described here, the nebulizer can beremoved from the circuit very easily, with no interruption of air flow,and no break in the ventilator circuit.

An alternative embodiment of the ventilator circuit is shown in FIGS.5-9, with a different configuration of the humidifier, T-fitting, andthree-way valve. In this embodiment, self-sealing connections on theT-fitting are not used. Rather, a ball valve 126 positioned at the exitport of the nebulizer 101 is used instead. As shown in FIG. 6, thenebulization is active. In FIG. 6, the T-fitting is directing thebreathing gas flow to the nebulizer, and nebulization can take placewhen the nebulizer air flow in tube 118 is active. The Ball valve 126 isin the open position and allows breathing gases and nebulized drug toflow from the nebulizer to the inspiratory limb 107, effectivelybypassing the humidifier 121.

FIG. 7 shows the embodiment of FIG. 5 with the nebulizer bypassed.Three-way valve 105 is in the first position in FIG. 7, directing thebreathing gas flow through conduit 131 to humidifier 121. The breathinggas flow exits the humidifier and passes through T-fitting 106 toinspiratory limb 107 and on the patient. In FIG. 7, even though ballvalve 126 is open, there is no circuit through nebulizer 101, so it iseffectively bypassed.

FIG. 8 shows the embodiment of FIG. 5 wherein the nebulizer is isolatedfor removal. Three-way valve 105 is in the same position as in FIG. 7,directing the breathing gas to humidifier 121, and then to inspiratorylimb 107 where the breathing gas goes to the patient. In FIG. 8, ballvalve 126 is in the off position and marked 126′, which isolates thenebulizer totally from the circuit. The nebulizer is depicted as 101′,in broken lines, indicated it can be safely removed without interruptingthe breathing gas circuit.

FIG. 9 is a portion of a circuit of an embodiment similar to FIG. 5, butwith no humidifier. In this embodiment, humidification would be providedwith an HME (not shown). As shown in FIG. 9, the three-way valve is inthe second position, shunting the breathing gases to the nebulizer. Thebreathing gases and atomized drug are depicted by the arrows enteringinspiratory limb 107, where they would be directed to the patient.Alternatively, when the three-way valve is in the first position, thebreathing gases would flow through conduit 131 bypassing the nebulizer.The ball valve can also be turned off, as in FIG. 8, to isolate thenebulizer and allow it to be removed without interrupting the breathinggas circuit.

LEGEND FOR DRAWINGS

100 Ventilator circuit 101 Nebulizer 102 Mechanical ventilator 103Inspiratory port of the mechanical ventilator 104 Expiratory port of themechanical ventilator 105 three-way valve (stopcock) 106 T-fitting 107Inspiratory line 108 Breathing tube 109 Nebulizer spring-loaded tee 110Patient or simulated lungs 111 IM filter 112 Cascade impactor 113 Vacuumpump 114 Pressure sensor 115 Pressure sensor connection to the solenoid116 solenoid 117 Compressed air source 118 Compressed air tube 119Expiratory limb 120 Expiratory filter 121 Humidifier 122 Humidifierinlet 123 Humidifier outlet 124 Humidifier T-fitting valve 125 HME 126Tee ball valve 127 Y connector 128 Temperature sensor 129 Wire from thetemperature sensor to the humidifier 130 Tube from three-way valve tothe ventilator 131 Nebulizer bypass tube 132 spring-loaded self-sealingfitting in T-fitting

1-20. (canceled)
 21. A breath actuated jet nebulizer in a ventilatorcircuit apparatus for the administration of nebulized drugs through anendotracheal tube to a patient on a mechanical ventilator that providesbreathing gases for inhalation by the patient, comprising: a. Aventilator breathing circuit having a mechanical ventilator and aninspiratory limb and an expiratory limb, with a jet nebulizer on theinspiratory limb, wherein the jet nebulizer requires a pressurized airsupply to cause nebulization to occur; and b. A pressure sensor on theinspiratory limb, wherein the pressure sensor controls the pressurizedair supply to the nebulizer, such that pressurized air is only suppliedto the nebulizer when the patient is inhaling.
 22. A breath actuated jetnebulizer in a ventilator circuit apparatus for the administration ofnebulized drugs through an endotracheal tube to a patient on amechanical ventilator that provides breathing gases for inhalation bythe patient, comprising: a. A ventilator breathing circuit having amechanical ventilator and an inspiratory limb and an expiratory limb,with a jet nebulizer on the inspiratory limb, wherein the jet nebulizerrequires a pressurized air supply to cause nebulization to occur; and b.A pressure sensor on the inspiratory limb, wherein the pressure sensorcontrols the pressurized air supply to the nebulizer, such thatpressurized air is only supplied to the nebulizer during a pressureincrease on the inspiratory limb caused by an increase in air pressurefrom the ventilator to force an inhalation by the patient.
 23. Theapparatus of claim 22, wherein the pressure sensor is adjacent to theventilator.
 24. A method of administering an inhaled drug to a patienton a mechanical ventilator, comprising a ventilator breathing circuithaving a mechanical ventilator and an inspiratory limb and an expiratorylimb; wherein a nebulizer and a pressure sensor are provided on theinspiratory limb, wherein the pressure sensor controls a pressurized airsupply to the nebulizer required for nebulization to occur, such thatpressurized air is only supplied to the nebulizer during a portion ofthe breathing cycle when the patient is inhaling, thereby nebulizingdrug that is administered to the patient only when the patient is on aninhalation portion of a breathing cycle.
 25. A method of administeringan inhaled drug to a patient on a mechanical ventilator, comprising aventilator breathing circuit having a mechanical ventilator and aninspiratory limb and an expiratory limb; wherein a nebulizer and apressure sensor are provided on the inspiratory limb, wherein thepressure sensor controls a pressurized air supply to the nebulizerrequired for nebulization to occur, such that pressurized air is onlysupplied to the nebulizer during a pressure increase on the inspiratorylimb caused by an increase in air pressure from the ventilator to forcean inhalation by the patient, thereby nebulizing drug that isadministered to the patient only when the patient is on an inhalationportion of a breathing cycle.
 26. The apparatus of claim 21, wherein thepressure sensor is adjacent to the ventilator.